Ball pen



FIG. 1 is a front elevational view of a ball pen, showing our new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a right-side elevational view thereof;

FIG. 6 is a left-side elevational view thereof; and,

FIG. 7 is a perspective view thereof. 

I claim the ornamental design for a ball pen, as shown and described. 